<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        :root {
            --primary-color: #2492fc;
        }

        div {
            /* background: #2492fc; */
            box-shadow: 0 10px 15px 0 
                        rgba(255,255,0, 0.3);
        }
    </style>
</head>

<body>
    <div>1234</div>
</body>

</html>